Messages in this thread | | | Subject | Re: [PATCH v9 2/3] PCI: Add tango PCIe host bridge support | From | Mason <> | Date | Wed, 5 Jul 2017 01:59:55 +0200 |
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On 03/07/2017 20:11, Russell King - ARM Linux wrote:
> I don't think there's an easy solution to this problem - and I'm not > sure that stop_machine() can be made to work in this path (which > needs a process context). I have a suspicion that the Sigma Designs > PCI implementation is just soo insane that it's never going to work > reliably in a multi-SoC kernel without introducing severe performance > issues for everyone else.
If I remember correctly, this is the second HW block from tango that has been deemed "too insane for Linux".
The first one was the DMA engine, which doesn't interrupt when a transfer is done, but when a new transfer may be programmed. (Though there is a simple work-around for this one, if we give up command pipelining.)
Do larger SoC vendors have HW devs working closely with Linux devs, to avoid these design bloopers?
Regards.
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